Method for manufacturing very low roughness electrodeposited copper foil and electrodeposited copper foil manufactured thereby

ABSTRACT

The present invention relates to a method for manufacturing a low roughness electrodeposited copper foil, and an electrodeposited copper foil manufactured thereby, and uses an electrolyte which basically consists of a sulfuric acid, a copper ion and a chloride ion is adapted with an additive which consists of a HEC (Hydroxyethyl Cellulose) of 0.05˜50 ppm, a SPS (bis(sodiumsulfopropyl)disulfide) of 0.05˜20 ppm, and a gelatin of 0.1˜100 ppm. The present invention is adapted to manufacture a low roughness electrodeposited copper foil using a conventional copper foil manufacture facility and the electrodeposited copper foil according to the present invention is adapted as a material for a copper clad laminate for a printed circuit substrate and an electrode material for a lithium ion battery.

RELATED U.S. APPLICATIONS

[0001] Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

REFERENCE TO MICROFICHE APPENDIX

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] The present invention relates to a method for manufacturing anelectrodeposited copper foil adhered to a prepreg for a PCB(PrintedCircuit Board) and an electrodeposited copper foil manufactured thereby,and in particular to a method for manufacturing an electrodepositedcopper foil which does not have a residual copper by decreasing aroughness of a matte side of an electrodeposited copper foil even when afine pattern is formed.

BACKGROUND OF THE INVENTION

[0005] Generally, a PCB is widely used in a home appliance such as aradio, television, washing machine, VCR, etc., and an industrialelectric/electronic instrument such as a computer, wirelesscommunication instrument, various controllers, etc. The PCB is formed ofan insulated substrate such as a prepreg of a frame retardant formed insuch a manner that a glass fiber is impregnated in foil is adhered to aninsulation substrate at a high temperature and pressure, and then theelectrodeposited copper foil is etched based on a circuit design.

[0006] The electrodeposited copper foil adhered to the insulationsubstrate is manufactured by the following processes. A raw foil ismanufactured in a copper sulphate solution by a continuouselectrodepositing method. Next, a nodule process is performed withrespect to a raw copper foil for forming a copper nodule for therebyenhancing an adhesion to an insulation substrate and a barrier layer isformed on the copper foil surface. Finally, a corrosion resistchromating process is performed.

[0007] Recently, as an electric/electro instrument is made thin, aprinted circuit for a substrate need have a fine and high intensive andcompact construction. For this, a method for developing a very lowroughness copper foil has been provided.

[0008] In a conventional electrodeposited copper foil manufacturingmethod, a first method is to divide an electrolytic section into twosections and then to enhance a current density of a second sectionrather than a first section for thereby obtaining a low roughness copperfoil.

[0009] A super anode is attached to a foil manufacturing apparatus ofthe above manufacturing facility. In the case that the super anode isadapted, it is possible to change the size of a nucleus when a nucleusis initially generated by adjusting the current applied to the superanode and the main anode. Therefore, it is possible to manufacture thelow roughness copper foil by accurately adjusting the size of theinitial nucleus. However, it is impossible to manufacture a lowroughness copper foil corresponding to the recent fine circuit patternwith the above described method.

[0010] A second method is directed to decreasing the concentration of achloride ion in an electrolyte below 1 ppm for thereby obtaining a lowroughness copper foil. However, it is possible to decrease theconcentration of a chloride ion below 1ppm based on only an experimentalcondition. In the case that the electrodeposited copper foil ismanufactured, a copper scrap is generally used as a source material.When the copper scrap is used for the mass production system, there isno suitable economic method for preventing a chloride ion generated by awaste electric wire. Therefore, it is impossible to implement an actualpracticality.

[0011] A third method is directed to obtaining a low roughness copperfoil by mechanically polishing a conventional electrodeposited copperfoil through a buffing method. However, the above method is needed tohave an additional manufacturing facility. If there is a surplus duringthe buffing process, a residual copper may be formed during themanufacture of the PCB.

[0012] A fourth method is directed to adjusting morphology of a copperfoil by changing an additive added to an electrolyte. In more detail,the above fourth method is directed to implementing a low roughnesscopper foil by adding a low molecular weight water-soluble celluloseether, a low molecular weight water-soluble polyalkylene glycol ether, alow molecular weight water-soluble polyethyleneimine, and a watersoluble sulfonated organic sulfur compound. In the above method, it ispossible to manufacture a low roughness copper foil by changing only anadditive of an electrolyte without changing or modifying a conventionalcopper manufacture apparatus. In addition, a mechanical polishingprocess like a buffing process is not needed. It is not needed to managea chloride ion at a very low degree. The above method is more economicalcompared to the other methods.

[0013] However, since the copper foil manufactured by the above methodhas a roughness Rz of a matte side of 3.81 μm, the above method does notsatisfy the demand of the recent low roughness copper foil.

[0014] A fifth method is directed to manufacturing a low roughnesscopper foil using an electrolyte including a small amount ofpolyethylene glycol, tin ion, iron ion and a chloride ion of below 0.1ppm. In the above method, there is a limit for substantially maintainingthe concentration of the chloride ion below 0.1 ppm for a massproduction.

BRIEF SUMMARY OF THE INVENTION

[0015] Accordingly, it is a first object of the present invention toprovide a method for manufacturing a low roughness electrodepositedcopper foil and an electrodeposited copper foil manufactured by themethod which does not need a design change or modification of aconventional copper manufacture apparatus and directly uses a sourcematerial of a low cost waste electric wire without using a conventionalfacility like a mechanical polishing apparatus and an additional processand is capable of manufacturing an electrodeposited copper foil having alow roughness by adjusting the amount of an additive.

[0016] It is a second object of the present invention to provide amethod for manufacturing a low roughness electrodeposited copper foiland an electrodeposited copper foil manufactured by the same which arewell adapted to an electrode of a lithium ion battery or copper cladlaminates which is used in an electronic instrument such as a PCB and aflexible circuit substrate, etc.

[0017] To achieve the above objects, in a method for manufacturing anelectrodeposited copper foil in which a rotating drum and an anode plateformed of a curve distanced from an outer surface of the drum by acertain distance are drowned in an electrolyte, said electrolyteconsists of a sulfuric acid, copper ion and chloride ion, and anelectrodeposited copper foil is deposited on a surface of the drum as anegative current is applied to the drum and a positive current isapplied to the anode plate, there is provided a method for manufacturingan electrodeposited copper foil which is characterized in that anadditive which consists of a gelatin of 0.1˜100 ppm, a HEC(HydroxyethylCellulose) of 0.05 ppm˜50 ppm, and aSPS(bis(sodiumsulfopropyl)disulfide) of 0.05˜20 ppm is added to theelectrolyte.

[0018] The amount of the addition of the gelatin is preferably 2˜5 ppm.The amount of the addition of the HEC is preferably 1˜3 ppm. The amountof the addition of the SPS is preferably 0.5˜3 ppm.

[0019] The molecular weight of the gelatin is preferably above 10000.

[0020] There is preferably further provided a post-treatment for forminga nodule on one surface or both surfaces of the electrodeposited copperfoil.

[0021] A roughness of a matte side of the electrodeposited copper foilis larger than that of a shiny side.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022] The present invention will become better understood withreference to the accompanying drawings which are given only by way ofillustration and thus are not limitative of the present invention,wherein;

[0023]FIG. 1 is a view illustrating the construction of a coppermanufacture apparatus for describing a method for manufacturing anelectrodeposited copper foil according to the present invention;

[0024]FIG. 2 is a picture obtained by photographing an electrodepositedcopper foil manufactured according to an embodiment 1 of the presentinvention using a SEM; and

[0025]FIG. 3 is a picture obtained by photographing an electrodepositedcopper foil manufactured according to a comparison example 2 using aSEM.

DETAILED DESCRIPTION OF THE INVENTION

[0026]FIG. 1 is a view illustrating a copper foil manufacture apparatusfor describing a method for manufacturing an electrodeposited copperfoil according to the present invention.

[0027] As shown in FIG. 1, the copper foil manufacture apparatus isconstructed in such a manner that a rotating drum 100 and a circularshaped anode plate 200 are spaced apart by a certain distance. Here, thedrum 100 and the anode plate 200 are provided within a tank 500 havingan electrolyte 600.

[0028] Here, a lower portion of the rotation center of the drum 100 isdrowned in the electrolyte 600. The anode plate 200 is drowned in theelectrolyte 600 in such a manner that the drowned shape of the drum 100corresponds to the drowned shape of the anode plate 200. The negativeand positive currents are applied to the drum 100 and the anode plate200, respectively.

[0029] Preferably, the electrolyte 600 filled in the tank 500 consistsof H₂SO₄ of about 50˜200 g/l, Cu²⁺ of about 30˜150 g/l, and Cl⁻ of belowabout 200 mg/l. The temperature of the electrolyte 600 is about 20˜80°C., and the current density is about 20˜150 A/dm².

[0030] An electrolytic process is performed between the drum 100 and theanode plate 200, such that an electrodeposited copper foil 400 isdeposited on a surface of the drum 100. The electrodeposited copper foil400 is rolled up by the roller 300 installed in the upper right side.

[0031] A certain additive is usually provided into the electrolyte 600for adjusting a material property of the electrodeposited copper foil400 in the above method. In the present invention, the electrodepositedcopper foil 400 having a fine circuit pattern is manufactured by using agelatin, and HEC(Hydroxyethyl cellulose),SPS(bis(sodiumsulfopropyl)disulfide) as an additive. In addition, a lowroughness electrodeposited copper foil 400 which may be used as anelectrode material of a lithium ion battery is manufactured.

[0032] The gelatin used as an additive is a kind of a drived protein andhas a molecular weight of above 10000. If the gelatin having molecularweight below 10000 is used, an interaction between SPS and HEC isweakened, so that an electrodeposited copper foil having ununiformroughness and gloss is manufactured. In the case that the molecularweight of the gelatin is above 10000, it is possible to manufacture alow roughness copper foil having a uniform roughness and gloss.

[0033] The amount of the addition of the gelatin is minimum about 0.1ppm through maximum about 100 ppm. Preferably, the amount range of theaddition of the gelatin is about 1˜10 ppm. More preferably, the amountrange of the same is about 2˜5 ppm.

[0034] If the gelatin is added below 0.1 ppm in the electrolyte 600,more delicate initial structure may be obtained, but an electrodepositedcopper foil with high roughness is obtained by promoting the growth ofthe copper foil 400. Accordingly, an electrodeposited copper foil withlow roughness cannot be manufactured. On the other hand, if the gelatinis added above 100 ppm, an electrodeposited copper foil with lowroughness may be obtained, but the characteristic of HTE(HighTemperature Elongation, measured at 180° C.) which is one of theimportant characteristics of the copper foil can be deteriorated.

[0035] The amount of the addition of the HEC is minimum about 0.05 ppmthrough maximum about 50 ppm. Preferably, the amount range of theaddition of the HEC is about 0.5˜5 ppm. More preferably, the amountrange of the same is about 1-3 ppm. In the case that the HEC is addedwith the SPS and the gelatin in the electrolyte 600, an electrodepositedcopper foil with a lower roughness can be manufactured by an interactionof the additives.

[0036] If the HEC is added below 0.05 ppm in the electrolyte, a uniformelectrodeposited copper foil may not be manufactured due to the decreaseof the interaction. On the other hand, if the HEC is added above 50 ppm,protrusion may be extracted from the electrodeposited copper foil. Inthe case that copper clad laminates are produced by the electrodepositedcopper foil with protrusion and then a PCB(Printed Circuit Board) isproduced by the above copper clad laminates, the inferiority of the PCBis caused.

[0037] The amount of the addition of the SPS is minimum about 0.05 ppmthrough maximum about 20 ppm. Preferably, the amount range of theaddition of the SPS is about 0.1˜10 ppm. More peferably, the amountrange of the same is about 0.5˜3 ppm. The SPS is a material used as abrightener for an electrodepositing process. In the case that the SPS isadded into the electrolyte 600, it is possible to decrease the roughnessof the electrodeposited copper foil in accordance with an interactionwith the HEC and the gelatin.

[0038] If the SPS is added by below 0.05 ppm, the ability of theinteraction is decreased, so that an electrodeposited copper foil 400having ununiform roughness is manufactured. On the other hand, if theSPS is added by the amount of above 20 ppm, there is not a certaineffect, but the cost is increased.

[0039] Three embodiments for manufacturing an electrodeposited copperfoil 400 in such a manner that the amounts of the gelatin, HEC, and SPSadded to the electrolyte 600 as an additive are different by the unit ofppm will be described in the following.

[0040] According to the embodiments of the present invention, theelectrolysis condition is as follows. The electrolyte 600 basicallyconsists of H₂SO₄ of about 100 g/l, Cu²⁺ of about 100 g/l, and Cl⁻ ofbelow about 30 mg/l. The temperature of the electrolyte 600 is about 60°C., and the current density is about 100 A/dm².

[0041] The amounts of the additives added to the electrolyte 600 areshown in Table 1. TABLE 1 Gelatin HEC SPS Embodiment 1 2.5 ppm 3 ppm 1.5ppm Embodiment 2 3.5 ppm 1 ppm 2.5 ppm Embodiment 3 4.5 ppm 2 ppm 0.5ppm

[0042] In the following, the comparison example 1 that HEC is not addedas an additive and the comparison example 2 that Thiourea is newly addedwithout adding HEC and SPS will be described. The comparison examplesare performed for comparing the material properties of theelectrodeposited copper foil 400 which is manufactured when theadditives according to the present invention are all added with those ofthe electrodeposited copper foil which is manufactured when a certainadditive among the additives according to the present invention is notadded.

[0043] The electrolysis condition of the electrolyte of the comparisonsexcept for the components of the additives is the same as theelectrolysis condition of the electrolyte of the above embodiments ofthe present invention. The amounts of the additives added are shown inTable 2. TABLE 2 Gelatin HEC SPS Thiourea Comparison example 1 2.5 ppm —1.5 ppm — Comparison example 2 3.5 ppm — — 0.4 ppm

[0044]FIG. 2 is a picture obtained by photographing an electrodepositedcopper foil manufactured according to an embodiment 1 of the presentinvention using a SEM, and FIG. 3 is a picture obtained by photographingan electrodeposited copper foil manufactured according to a comparisonexample 2 using a SEM. As shown therein, FIGS. 2 and 3 illustrate thepictures of the SEM of the electrodeposited copper foil manufacturedbased on the embodiment 1 of the present invention and theelectrodeposited copper foil manufactured based on the comparisonexample 2, respectively, before the post-treatments are performed.

[0045] As shown in FIGS. 2 and 3, it is known that the electrodepositedcopper foil 400 manufactured based on the embodiment 1 of the presentinvention has a more smooth surface compared to the surface of theelectrodeposited copper foil manufactured based on the comparisonexample 2. The above consequence represents that the roughness of thesurface of the electrodeposited copper foil 400 manufactured based onthe embodiment 1 of the present invention is relatively lower than thatof the electrodeposited copper foil 400 manufactured based on thecomparison example 2.

[0046] In Table 3, there are a roughness, tensile strength, elongation,high temperature tensile strength, and high temperature elongation ofthe electrodeposited copper foil manufactured based on each embodimentof the present invention and the electrodeposited copper foilmanufactured based on each comparison example. TABLE 3 High High temper-Rough- Tensile Elon- temperature ature ness strength gation tensilestrength elonga- Rz(μm) (kgf/mm²) (%) (kgf/mm²) tion(%) Embodiment 1 1.833.3 15.9 18.3 16.3 Embodiment 2 1.6 34.6 18.1 18.2 15.1 Embodiment 32.1 32.8 16.3 19.1 15.3 Comparison 2.5 34.1 5.8 20.1 8.5 example 1Comparison 3.5 33.8 8.3 20.3 2.1 example 2

[0047] As shown in Table 3, it is known that the roughness of theelectrodeposited copper foils manufactured according to the embodiments1 through 3 are 1.61 μm through 2.1 pm, and the roughness of theelectrodeposited copper foils manufactured according to the comparisonexamples 1 through 2 are about 2.5 pm through 3.5 μm. As a result, it isknown that the electrodeposited copper foils manufactured according tothe preferred embodiments of the present invention have a lowerroughness, respectively, compared to the roughness of theelectrodeposited copper foils manufactured according to the comparisonexamples.

[0048] The electrodeposited copper foil manufactured according to thepresent invention can be implemented with a conventional post-treatmentfor manufacturing the copper clad laminates which is used for printedcircuit substrate.

[0049] As a conventional post-treatment of the electrodeposited copperfoil 400, there are a nodule process adapted to further form a nodule onone side or both sides of the electrodeposited copper foil forincreasing an adhesion with a resin, a barrier process adapted toprevent a copper from being diffused into a resin layer, a corrosionresisting process adapted to prevent an oxidation of a copper foil, anda silane coupling agent process adapted to enhance a adhesionreliability when being adhered with a resin.

[0050] In addition, the electrodeposited copper foil 400 manufacturedaccording to the present invention is formed of a copper clad laminatewith an insulation film layer and an adhesive layer. The copper cladlaminate is etched based on a circuit design and is adapted tomanufacture a printed circuit substrate.

[0051] In the method for manufacturing a low roughness electrodepositedcopper foil and an electrodeposited copper foil manufactured thereby,the amounts of additives cited in each embodiment are not limitedthereto. In the present invention, various embodiments may beimplemented in the addition ranges of the additives cited in the presentinvention. The electrodeposited copper foils 400 having various materialproperties may be adapted to the production of the copper clad laminateand the circuit substrate.

[0052] As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described examples are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the meets and bounds of theclaims, or equivalences of such meets and bounds are therefore intendedto be embraced by the appended claims.

We claim:
 1. In a method for manufacturing an electrodeposited copperfoil in which a rotating drum and an anode plate which is formed of acurve distanced from the outer surface of the drum by a certain distanceare drowned in an electrolyte, said electrolyte consists of a sulfuricacid, copper ion and chloride ion, and the electrodeposited copper foilis deposited on the surface of the drum as a negative current is appliedto the drum, and a positive current is applied to the anode plate, amethod for manufacturing an electrodeposited copper foil which ischaracterized in that an additive which consists of a gelatin of 0.1˜100ppm, a HEC(Hydroxyethyl Cellulose) of 0.05 ppm˜50 ppm, and aSPS(bis(sodiumsulfopropyl)disulfide) of 0.05˜20 ppm is added to theelectrolyte.
 2. The method of claim 1, wherein the amount of theaddition of the gelatin is 2˜5 ppm.
 3. The method of claim 1, whereinthe amount of the addition of the HEC is 1˜3 ppm.
 4. The method of claim1, wherein the amount of the addition of the SPS is 0.5˜3 ppm.
 5. Themethod of one among claims 1 through 4, wherein a roughness of a matteside of the electrodeposited copper foil is larger than a roughness of ashiny side.
 6. The method of one among claims 1 through 4, furthercomprising a post-treatment process.
 7. The method of claim 6, whereinsaid post-treatment process is formed of one or more than one selectedfrom the steps of: a nodule process for forming a nodule on one side orboth sides of the electrodeposited copper foil for increasing anadhesion with a resin; a barrier process for preventing a copper frombeing diffused into a resin layer; a corrosion resisting process forpreventing an oxidation of the electrodeposited copper foil; and asilane coupling agent process for enhancing an adhesion reliability withthe resin.
 8. The method of either claim 1 or claim 2, wherein amolecular weight of the gelatin is above
 10000. 9. The method of claim1, wherein said electrolyte is formed of a sulfuric acid of 50˜200 g/l,a copper ion of 30˜150 g/l, and a chloride ion of 200 mg/l.
 10. Themethod of claim 9, wherein a temperature of the electrolyte is 20˜80° C.11. The method of claim 9, wherein a current density of the electrolyteis 20˜150 A/dm².
 12. A low roughness electrodeposited copper foilmanufactured by one method selected from the claims 1 through
 4. 13. Thefoil of claim 12, wherein a roughness of a matte side of theelectrodeposited copper foil is larger than a roughness of a shiny side.14. The foil of claim 12, further comprising a post-treatment process.15. The foil of claim 14, wherein said post-treatment process is formedof one or more than one selected from the steps of: a nodule process forforming a nodule on one side or both sides of the electrodepositedcopper foil for increasing an adhesion with a resin; a barrier processfor preventing a copper from being diffused into a resin layer; acorrosion resisting process for preventing an oxidation of theelectrodeposited copper foil; and a silane coupling agent process forenhancing an adhesion reliability with the resin.